Zoom optical system, optical apparatus and method for manufacturing the zoom optical system

ABSTRACT

A variable power optical system (ZL (1)) includes a plurality of lens groups (G 1 -G 7 ). During variable magnification, an interval between adjacent lens groups changes. The plurality of lens groups include: a first focusing lens group (G 5 ) that moves during focusing; and a second focusing lens group (G 6 ) that is disposed more toward an imaging surface side than the first focusing lens group and that moves along a different trajectory than the first focusing lens group during focusing. The first focusing lens group and the second focusing lens group both have a negative refractive power. The plurality of lens groups satisfy the following condition: 0.40&lt;fF1/fF2&lt;3.50 (wherein fF1 is the focal distance of the first focusing lens group, and fF2 is the focal distance of the second focusing lens group).

TECHNICAL FIELD

The present invention relates to a zoom optical system, an opticalapparatus and a method for manufacturing the zoom optical system.

TECHNICAL BACKGROUND

Conventionally, zoom optical systems suitable for photographic cameras,electronic still cameras, video cameras and the like have been proposed(for example, see Patent literature 1). The zoom optical systems arerequired to reduce the weight of a focusing lens group, and suppressvariation in aberrations during focusing.

PRIOR ARTS LIST Patent Document

Patent literature 1: Japanese Laid-Open Patent Publication No.2013−160944(A)

SUMMARY OF THE INVENTION

The present invention proposes a zoom optical system described below,and an optical apparatus mounted with the zoom optical system. A zoomoptical system according to the present invention comprises a pluralityof lens groups, wherein distances between adjacent lens groups among theplurality of lens groups change upon zooming. The plurality of lensgroups include: a first focusing lens group that moves upon focusing;and a second focusing lens group that is disposed closer to an imagesurface than the first focusing lens group, and moves on a trajectorydifferent from a trajectory of the first lens group upon focusing. Thefirst focusing lens group and the second focusing lens group each have anegative refractive power. The plurality of lens groups are configuredso as to satisfy the following conditional expression.

0.40<fF1/fF2<3.50

where

fF1: a focal length of the first focusing lens group, and

fF2: a focal length of the second focusing lens group.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a lens configuration of a zoom optical system according toa first example;

FIGS. 2A, 2B and 2C are graphs respectively showing various aberrationsof the zoom optical system according to the first example upon focusingon infinity in the wide-angle end state, the intermediate focal lengthstate and the telephoto end state;

FIGS. 3A, 3B and 3C are graphs respectively showing various aberrationsof the zoom optical system according to the first example upon focusingon a short distant object in the wide-angle end state, the intermediatefocal length state and the telephoto end state;

FIG. 4 shows a lens configuration of a zoom optical system according toa second example;

FIGS. 5A, 5B and 5C are graphs respectively showing various aberrationsof the zoom optical system according to the second example upon focusingon infinity in the wide-angle end state, the intermediate focal lengthstate and the telephoto end state;

FIGS. 6A, 6B and 6C are graphs respectively showing various aberrationsof the zoom optical system according to the second example upon focusingon a short distant object in the wide-angle end state, the intermediatefocal length state and the telephoto end state;

FIG. 7 shows a lens configuration of a zoom optical system according toa third example;

FIGS. 8A, 8B and 8C are graphs respectively showing various aberrationsof the zoom optical system according to the third example upon focusingon infinity in the wide-angle end state, the intermediate focal lengthstate and the telephoto end state;

FIGS. 9A, 9B and 9C are graphs respectively showing various aberrationsof the zoom optical system according to the third example upon focusingon a short distant object in the wide-angle end state, the intermediatefocal length state and the telephoto end state;

FIG. 10 shows a lens configuration of a zoom optical system according toa fourth example;

FIGS. 11A, 11B and 11C are graphs respectively showing variousaberrations of the zoom optical system according to the fourth exampleupon focusing on infinity in the wide-angle end state, the intermediatefocal length state and the telephoto end state;

FIGS. 12A, 12B and 12C are graphs respectively showing variousaberrations of the zoom optical system according to the fourth exampleupon focusing on a short distant object in the wide-angle end state, theintermediate focal length state and the telephoto end state;

FIG. 13 shows a lens configuration of a zoom optical system according toa fifth example;

FIGS. 14A, 14B and 14C are graphs respectively showing variousaberrations of the zoom optical system according to the fifth exampleupon focusing on infinity in the wide-angle end state, the intermediatefocal length state and the telephoto end state;

FIGS. 15A, 15B and 15C are graphs respectively showing variousaberrations of the zoom optical system according to the fifth exampleupon focusing on a short distant object in the wide-angle end state, theintermediate focal length state and the telephoto end state;

FIG. 16 shows a configuration of a digital camera that is an embodimentof an optical apparatus; and

FIG. 17 is a flowchart showing a method for manufacturing the zoomoptical system.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments for implementing the present invention arehereinafter described.

FIG. 16 shows a schematic configuration of a digital camera that is anembodiment of an optical apparatus of the present invention. This cameraincludes a main body 1 mounted with an image pickup element 3, and aphotographic lens 2 equivalent to an embodiment of a zoom optical systemof the present invention. Light from an object (photographic subject),not shown, is collected by the photographing lens 2, and reaches animage pickup element 3. Accordingly, the light from the photographicsubject is captured by the image pickup element 3, and is recorded as aphotographic subject image in a memory, not shown. The details of thephotographic lens 2 are hereinafter described as an embodiment of a zoomoptical system.

A zoom optical system according to one embodiment of the presentinvention comprises a plurality of lens groups whose distances betweenadjacent lens groups change upon zooming. The plurality of lens groupsinclude: a first focusing lens group and a second focusing lens groupthat respectively move on trajectories different from each other uponfocusing. The second focusing lens group is disposed closer to an imagesurface than the first focusing lens group, and the first focusing lensgroup and the second focusing lens group each have a negative refractivepower. The plurality of lens groups are configured so as to satisfy thefollowing conditional expression (1).

0.40<fF1/fF2<3.50   (1)

where

fF1: a focal length of the first focusing lens group, and

fF2: a focal length of the second focusing lens group.

The conditional expression (1) described above defines the ratio betweenthe focal length of the first focusing lens group and the focal lengthof the second focusing lens group. By satisfying the conditionalexpression (1), the variation in various aberrations including thespherical aberration upon focusing from the infinity object to theshort-distant object can be suppressed.

If the corresponding value of the conditional expression (1) exceeds theupper limit value of 3.50, the refractive power of the second focusinglens group becomes strong. Accordingly, it is difficult to suppress thevariation in various aberrations including the spherical aberration uponfocusing from the infinity object to the short distant object. To securethe advantageous effects of this embodiment, it is preferable to set theupper limit value of the conditional expression (1) to 3.45, 3.40 or3.35. When the upper limit value of the conditional expression (1) isset to a smaller value, e.g., 3.30, 3.25, 3.20, 3.15, 3.10, or 3.05, theadvantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (1) falls below the lower limit value of 0.40, the refractivepower of the first focusing lens group becomes strong. Accordingly, itis difficult to suppress the variation in various aberrations includingthe spherical aberration upon focusing from the infinity object to theshort distant object. To secure the advantageous effects of thisembodiment, it is preferable to set the lower limit value of theconditional expression (1) to 0.45. When the lower limit value of theconditional expression (1) is set to a larger value, e.g., 0.50, 0.55,0.60, 0.65, 0.70, 0.75, 0.80, 0.85, or 0.88, the advantageous effects ofthis embodiment are further secured.

The zoom optical system having the configuration described abovefacilitates favorable aberration correction by changing the distancesbetween the adjacent lens groups upon zooming, and arranges theplurality of focusing lens groups having refractive powers, which cansuppress the variation in various aberrations including the sphericalaberration upon focusing from the infinity object to the short-distantobject, without increasing the sizes of the focusing lens groups.

Preferably, the zoom optical system further satisfies the followingconditional expression (2).

0.20<(−fFs)/ft<2.00   (2)

where

fFs: a focal length of either the first focusing lens group or thesecond focusing lens group which has a stronger refractive power thanthe other, and

ft: a focal length of the zoom optical system in a telephoto end state.

The conditional expression (2) defines the ratio between the focallength of a focusing lens group having a stronger refractive powerbetween the first focusing lens group and the second focusing lens groupand the focal length of the zoom optical system in the telephoto endstate. By satisfying the conditional expression (2), the variation invarious aberrations including the spherical aberration upon focusingfrom the infinity object to the short-distant object in the telephotoend state can be suppressed without increasing the size of the lensbarrel.

If the corresponding value of the conditional expression (2) exceeds theupper limit value of 2.00, the refractive power of the focusing lensgroup becomes weak. Accordingly, the amount of movement of the focusinglens group upon focusing from the infinity object to the short distantobject becomes large, thereby increasing the size of the lens barrel. Tosecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (2) to 1.90.When the upper limit value of the conditional expression (2) is set to asmaller value, e.g., 1.80, 1.65, 1.50, 1.35, 1.25, 1.20, 1.10, or 1.05,the advantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (2) falls below the lower limit value of 0.20, the refractivepower of the focusing lens group becomes strong. Accordingly, it isdifficult to suppress the variation in various aberrations including thespherical aberration upon focusing from the infinity object to the shortdistant object in the telephoto end state. To secure the advantageouseffects of this embodiment, it is preferable to set the lower limitvalue of the conditional expression (2) to 0.25. When the lower limitvalue of the conditional expression (2) is set to a larger value, e.g.,0.30, 0.35, 0.40, 0.43, 0.45, 0.48, 0.50, 0.53, or 0.55, theadvantageous effects of this embodiment are further secured.

Preferably, the first focusing lens group moves in a direction towardthe image surface upon focusing from an infinity object to a shortdistant object. Accordingly, the variation in various aberrationsincluding the spherical aberration upon focusing from the infinityobject to the short-distant object can be effectively suppressed.

Preferably, the second focusing lens group moves in a direction towardthe image surface upon focusing from an infinity object to a shortdistant object. Accordingly, the variation in various aberrationsincluding the spherical aberration upon focusing from the infinityobject to the short-distant object can be further effectivelysuppressed.

Preferably, the zoom optical system further satisfies the followingconditional expression (3).

1.00<(−fFs)/fw<4.00   (3)

where

fFs: a focal length of either the first focusing lens group or thesecond focusing lens group which has a stronger refractive power thanthe other, and

fw: a focal length of the zoom optical system in a wide angle end state.

The conditional expression (3) defines the ratio between the focallength of a focusing lens group having a stronger refractive powerbetween the first focusing lens group and the second focusing lens groupand the focal length of the zoom optical system in the wide angle endstate. By satisfying the conditional expression (3), the variation invarious aberrations including the spherical aberration upon focusingfrom the infinity object to the short-distant object in the wide angleend state can be suppressed without increasing the size of the lensbarrel.

If the corresponding value of the conditional expression (3) exceeds theupper limit value of 4.00, the refractive power of the focusing lensgroup becomes weak. Accordingly, the amount of movement of the focusinglens group upon focusing from the infinity object to the short distantobject becomes large, thereby increasing the size of the lens barrel. Tosecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (3) to 3.90.When the upper limit value of the conditional expression (3) is set to asmaller value, e.g., 3.80, 3.50, 3.30, 3.15, 3.00, 2.80, 2.50, 2.20, or2.00, the advantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (3) falls below the lower limit value of 1.00, the refractivepower of the focusing lens group becomes strong. Accordingly, it isdifficult to suppress the variation in various aberrations including thespherical aberration upon focusing from the infinity object to the shortdistant object in the wide angle end state. To secure the advantageouseffects of this embodiment, it is preferable to set the lower limitvalue of the conditional expression (3) to 1.10. When the lower limitvalue of the conditional expression (3) is set to a larger value, e.g.,1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, or 1.60, theadvantageous effects of this embodiment are further secured.

Preferably, the zoom optical system further satisfies the followingconditional expression (4).

0.10<MWF1/MWF2<3.00   (4)

where

MWF1: an absolute value of an amount of movement of the first focusinglens group upon focusing from an infinity object to a short distantobject in a wide angle end state, and

MWF2: an absolute value of an amount of movement of the second focusinglens group upon focusing from the infinity object to the short distantobject in the wide angle end state.

The conditional expression (4) defines the ratio between the absolutevalue of the amount of movement of the first focusing lens group uponfocusing from the infinity object to the short-distant object in thewide angle end state, and the absolute value of the amount of movementof the second focusing lens group upon focusing from the infinity objectto the short-distant object in the wide angle end state. By satisfyingthe conditional expression (4), the variation in various aberrationsincluding the spherical aberration upon focusing from the infinityobject to the short-distant object in the wide angle end state can besuppressed.

If the corresponding value of the conditional expression (4) exceeds theupper limit value of 3.00, the amount of movement of the first focusinglens group becomes too large. Accordingly, it is difficult to suppressthe variation in various aberrations including the spherical aberrationupon focusing from the infinity object to the short distant object inthe wide angle end state. To secure the advantageous effects of thisembodiment, it is preferable to set the upper limit value of theconditional expression (4) to 2.50. When the upper limit value of theconditional expression (4) is set to a smaller value, e.g., 2.00, 1.75,1.50, 1.30, 1.15, 1.00, 0.85, 0.80, or 0.75, the advantageous effects ofthis embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (4) falls below the lower limit value of 0.10, the amount ofmovement of the second focusing lens group becomes too large.Accordingly, it is difficult to suppress the variation in variousaberrations including the spherical aberration upon focusing from theinfinity object to the short distant object in the wide angle end state.To secure the advantageous effects of this embodiment, it is preferableto set the lower limit value of the conditional expression (4) to 0.13,0.15, 0.18, 0.20, 0.21, or 0.23. When the lower limit value of theconditional expression (4) is set to a larger value, e.g., 0.25, 0.30,0.35, or 0.38, the advantageous effects of this embodiment are furthersecured.

Preferably, the zoom optical system further satisfies the followingconditional expression (5).

0.20<βWF1/βWF2<5.00   (5)

where

βWF1: a lateral magnification of the first focusing lens group uponfocusing on an infinity object in a wide angle end state, and

βWF2: a lateral magnification of the second focusing lens group uponfocusing on the infinity object in the wide angle end state.

The conditional expression (5) defines the ratio between the lateralmagnification of the first focusing lens group upon focusing on theinfinity object in the wide angle end state, and the lateralmagnification of the second focusing lens group upon focusing on theinfinity object in the wide angle end state. By satisfying theconditional expression (5), the variation in various aberrationsincluding the spherical aberration upon focusing from the infinityobject to the short-distant object in the wide angle end state can besuppressed.

If the corresponding value of the conditional expression (5) exceeds theupper limit value of 5.00, the lateral magnification of the firstfocusing lens group upon focusing on the infinity object in the wideangle end state becomes too large. Accordingly, it is difficult tosuppress the variation in various aberrations including the sphericalaberration upon focusing from the infinity object to the short distantobject in the wide angle end state. To secure the advantageous effectsof this embodiment, it is preferable to set the upper limit value of theconditional expression (5) to 4.80. When the upper limit value of theconditional expression (5) is set to a smaller value, e.g., 4.60, 4.00,3.50, 3.30, 3.00, 2.50, 2.00, 1.50, or 1.25, the advantageous effects ofthis embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (5) falls below the lower limit value of 0.20, the lateralmagnification of the second focusing lens group upon focusing on theinfinity object in the wide angle end state becomes too large.Accordingly, it is difficult to suppress the variation in variousaberrations including the spherical aberration upon focusing from theinfinity object to the short distant object in the wide angle end state.To secure the advantageous effects of this embodiment, it is preferableto set the lower limit value of the conditional expression (5) to 0.30or 0.35. When the lower limit value of the conditional expression (5) isset to a larger value, e.g., 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70,or 0.75, the advantageous effects of this embodiment are furthersecured.

Preferably, the plurality of lens groups include a succeeding lens groupdisposed closer to the image surface than the second focusing lensgroup, and the succeeding lens group consists of at least one lensgroup. Accordingly, the variation in various aberrations including thespherical aberration upon focusing from the infinity object to theshort-distant object can be effectively suppressed.

Preferably, the zoom optical system further satisfies the followingconditional expression (6).

−2.00<(−fFs)/fR<2.00   (6)

where

fFs: a focal length of either the first focusing lens group or thesecond focusing lens group which has a stronger refractive power thanthe other, and

fR: a focal length of the succeeding lens group.

The conditional expression (6) defines the ratio between the focallength of a focusing lens group having a stronger refractive powerbetween the first focusing lens group and the second focusing lensgroup, and the focal length of the succeeding lens group. By satisfyingthe conditional expression (6), the variation in various aberrationsincluding the spherical aberration upon focusing from the infinityobject to the short-distant object can be suppressed.

If the corresponding value of the conditional expression (6) exceeds theupper limit value of 2.00, the positive refractive power of thesucceeding lens group becomes strong. Accordingly, it is difficult tosuppress the variation in various aberrations including the sphericalaberration upon focusing from the infinity object to the short distantobject. To secure the advantageous effects of this embodiment, it ispreferable to set the upper limit value of the conditional expression(6) to 1.90. When the upper limit value of the conditional expression(6) is set to a smaller value, e.g., 1.80, 1.65, 1.50, 1.35, 1.20, 1.10,1.10, 0.90, or 0.80, the advantageous effects of this embodiment arefurther secured.

On the other hand, if the corresponding value of the conditionalexpression (6) falls below the lower limit value of −2.00, the negativerefractive power of the succeeding lens group becomes strong.Accordingly, it is difficult to suppress the variation in variousaberrations including the spherical aberration upon focusing from theinfinity object to the short distant object. To secure the advantageouseffects of this embodiment, it is preferable to set the lower limitvalue of the conditional expression (6) to −1.90. When the lower limitvalue of the conditional expression (6) is set to a larger value, e.g.,−1.80, −1.65, −1.50, −1.25, −1.00, −0.75, −0.50, −0.25, or −0.10, theadvantageous effects of this embodiment are further secured.

Preferably, the plurality of lens groups include a preceding lens groupdisposed closer to an object than the first focusing lens group, and thepreceding lens group consists of at least one lens group. Accordingly,the variation in various aberrations including the spherical aberrationupon zooming from the wide-angle end state to the telephoto end statecan be effectively suppressed.

Preferably, the zoom optical system further satisfies the followingconditional expression (7).

0.30<(−fFs)/fF<3.00   (7)

where

fFs: a focal length of either the first focusing lens group or thesecond focusing lens group which has a stronger refractive power thanthe other, and

fF: a focal length of a lens group adjacent to the first focusing lensgroup in the preceding lens group.

The conditional expression (7) defines the ratio between the focallength of a focusing lens group having a stronger refractive powerbetween the first focusing lens group and the second focusing lensgroup, and the focal length of the preceding lens group. By satisfyingthe conditional expression (7), the variation in various aberrationsincluding the spherical aberration upon zooming from the wide-angle endstate to the telephoto end state can be suppressed without increasingthe size of the lens barrel.

If the corresponding value of the conditional expression (7) exceeds theupper limit value of 3.00, the refractive power of the preceding lensgroup becomes strong. Accordingly, it is difficult to suppress thevariation in various aberrations including the spherical aberration uponzooming from the wide-angle end state to the telephoto end state. Tosecure the advantageous effects of this embodiment, it is preferable toset the upper limit value of the conditional expression (7) to 2.90.When the upper limit value of the conditional expression (7) is set to asmaller value, e.g., 2.80, 2.65, 2.50, 2.30, 2.15, 2.00, 1.90, 1.85, or1.80, the advantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (7) falls below the lower limit value of 0.30, the refractivepower of the preceding lens group becomes weak. Accordingly, the amountof movement of the preceding lens group upon zooming from the wide-angleend state to the telephoto end state becomes large, thereby increasingthe size of the lens barrel. To secure the advantageous effects of thisembodiment, it is preferable to set the lower limit value of theconditional expression (7) to 0.40. When the lower limit value of theconditional expression (7) is set to a larger value, e.g., 0.50, 0.70,0.85, 1.00, 1.10, 1.15, 1.20, 1.25, or 1.30, the advantageous effects ofthis embodiment are further secured.

Preferably, the preceding lens groups include a first lens group thathas a positive refractive power and is disposed closest to an object.Accordingly, the variation in various aberrations including thespherical aberration upon zooming from the wide-angle end state to thetelephoto end state can be effectively suppressed.

Preferably, the preceding lens group includes a second lens group thathas a negative refractive power and is disposed adjacent to the firstlens group. Accordingly, the variation in various aberrations includingthe spherical aberration upon zooming from the wide-angle end state tothe telephoto end state can be effectively suppressed.

Preferably, the zoom optical system further satisfies the followingconditional expression (8).

4.00<f1/(−f2)<8.00   (8)

where

f1: a focal length of the first lens group, and

f2: a focal length of the second lens group.

The conditional expression (8) defines the ratio between the focallength of the first lens group and the focal length of the second lensgroup. By satisfying the conditional expression (8), the variation invarious aberrations including the spherical aberration upon zooming fromthe wide-angle end state to the telephoto end state can be suppressed.

If the corresponding value of the conditional expression (8) exceeds theupper limit value of 8.00, the refractive power of the second lens groupbecomes strong. Accordingly, it is difficult to suppress the variationin various aberrations including the spherical aberration upon zoomingfrom the wide-angle end state to the telephoto end state. To secure theadvantageous effects of this embodiment, it is preferable to set theupper limit value of the conditional expression (8) to 7.80. When theupper limit value of the conditional expression (8) is set to a smallervalue, e.g., 7.50, 7.25, 7.00, 6.75, 6.50, 6.30, 6.20, 6.10, or 6.00,the advantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (8) falls below the lower limit value of 4.00, the refractivepower of the first lens group becomes strong. Accordingly, it isdifficult to suppress the variation in various aberrations including thespherical aberration upon zooming from the wide-angle end state to thetelephoto end state. To secure the advantageous effects of thisembodiment, it is preferable to set the lower limit value of theconditional expression (8) to 4.20. When the lower limit value of theconditional expression (8) is set to a larger value, e.g., 4.50, 4.70,4.85, 5.00, 5.20, 5.40, 5.50, 5.60, or 5.70, the advantageous effects ofthis embodiment are further secured.

The zoom optical system has the configuration described above, which canfavorably suppress the aberration fluctuation upon zooming from a wideangle end state to a telephoto end state, while satisfying the followingconditional expression (9).

2ωw>75.0°  (9)

where

ωw: a half angle of view of the zoom optical system in a wide angle endstate.

According to the configuration described above, by narrowing down therange of the corresponding value of each conditional expression, thelower limit value of the conditional expression (9) can be set to alarger value, e.g., 77.0° , 80.0° , 82.0° or 83.5°.

Preferably, the zoom optical system further satisfies the followingconditional expression (10).

0.10<BFw/fw<1.00   (10)

where

BFw: an air equivalent distance (back focus) of the zoom optical systemin a wide-angle end state, and

fw: a focal length of the zoom optical system in a wide angle end state.

The conditional expression (10) defines the ratio between the back focusof the zoom optical system in the wide-angle end state, and the focallength of the zoom optical system in the wide-angle end state. Bysatisfying the conditional expression (10), the various aberrationsincluding the coma aberration in the wide-angle end state can beeffectively corrected.

If the corresponding value of the conditional expression (10) exceedsthe upper limit value of 1.00, the back focus in the wide angle endstate becomes large with respect to the focal length in the wide-angleend state. Accordingly, it is difficult to correct the variousaberrations including the coma aberration in the wide-angle end state.To secure the advantageous effects of this embodiment, it is preferableto set the upper limit value of the conditional expression (10) to 0.90or 0.85. When the upper limit value of the conditional expression (10)is set to a smaller value, e.g., 0.80, 0.75, 0.70, 0.65, 0.60, or 0.55,the advantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (10) falls below the lower limit value of 0.10, the backfocus in the wide angle end state becomes small with respect to thefocal length in the wide-angle end state. Accordingly, it is difficultto correct the various aberrations including the coma aberration in thewide-angle end state. To secure the advantageous effects of thisembodiment, it is preferable to set the lower limit value of theconditional expression (10) to 0.15, 0.20, or 0.25. When the lower limitvalue of the conditional expression (10) is set to a larger value, e.g.,0.30, 0.35, 0.38, 0.40, 0.42, or 0.45, the advantageous effects of thisembodiment are further secured.

Preferably, the second focusing lens group has a lens component having anegative refractive power, and the lens component satisfies thefollowing conditional expression (11). Here, “lens component” is used asa term that means each of a single lens and a cemented lens.

−2.00<(r2+r1)/(r2−r1)<6.00   (11)

Where

r1: a radius of curvature of a lens surface of the lens component on anobject side, and

r2: a radius of curvature of a lens surface of the lens component on animage side.

The conditional expression (11) defines the shape factor of the lenshaving a negative refractive power in the second focusing lens group. Bysatisfying the conditional expression (11), the variation in variousaberrations including the coma aberration upon focusing from theinfinity object to the short-distant object can be suppressed.

If the corresponding value of the conditional expression (11) exceedsthe upper limit value of 6.00, the power for correcting the comaaberration of the second focusing lens group is insufficient.Accordingly, it is difficult to suppress the variation in variousaberrations including the coma aberration upon focusing from theinfinity object to the short distant object. To secure the advantageouseffects of this embodiment, it is preferable to set the upper limitvalue of the conditional expression (11) to 5.50. When the upper limitvalue of the conditional expression (11) is set to a smaller value,e.g., 5.00, 4.75, 4.50, 4.25, 4.00, 3.70, 3.50, or 3.20, theadvantageous effects of this embodiment are further secured.

On the other hand, if the corresponding value of the conditionalexpression (11) falls below the lower limit value of −2.00, the powerfor correcting the coma aberration of the second focusing lens group isinsufficient. Accordingly, it is difficult to suppress the variation invarious aberrations including the coma aberration upon focusing from theinfinity object to the short distant object. To secure the advantageouseffects of this embodiment, it is preferable to set the lower limitvalue of the conditional expression (11) to −1.50. When the lower limitvalue of the conditional expression (11) is set to a larger value, e.g.,−1.00, −0.50, −0.10, −0.05, 0.05, 0.08, 0.12, 0.40, or 0.55, theadvantageous effects of this embodiment are further secured.

Preferably, the zoom optical system further satisfies the followingconditional expression (12).

1.05<βWF1<1.80   (12)

where

βWF1: a lateral magnification of the first focusing lens group uponfocusing on an infinity object in a wide angle end state.

The conditional expression (12) defines the lateral magnification of thefirst focusing lens group upon focusing on the infinity object in thewide angle end state. By satisfying the conditional expression (12), thevariation in various aberrations including the spherical aberration uponfocusing from the infinity object to the short-distant object in thewide angle end state can be suppressed.

If the corresponding value of the conditional expression (12) exceedsthe upper limit value of 1.80, the lateral magnification of the firstfocusing lens group upon focusing on the infinity object in the wideangle end state becomes too large. Accordingly, it is difficult tosuppress the variation in various aberrations including the sphericalaberration upon focusing from the infinity object to the short distantobject in the wide angle end state. To secure the advantageous effectsof this embodiment, it is preferable to set the upper limit value of theconditional expression (12) to 1.75. When the upper limit value of theconditional expression (12) is set to a smaller value, e.g., 1.70, 1.65,1.60, 1.58, 1.55, 1.53, 1.50 or 1.49, or further to 1.48, theadvantageous effects of this embodiment are further secured.

If the corresponding value of the conditional expression (12) fallsbelow the lower limit value of 1.05, the lateral magnification of thefirst focusing lens group upon focusing on the infinity object in thewide angle end state becomes too small. Accordingly, it is difficult tosuppress the variation in the distortion and the coma aberrationincluding the spherical aberration upon focusing from the infinityobject to the short distant object in the wide angle end state. Tosecure the advantageous effects of this embodiment, it is preferable toset the lower limit value of the conditional expression (12) to 1.06.When the lower limit value of the conditional expression (12) is set to1.08, 1.10, 1.12, 1.15, 1.16, 1.20 or 1.22, or further to 1.25, theadvantageous effects of this embodiment are further secured.

Preferably, the zoom optical system further satisfies the followingconditional expression (13).

1.05<βWF2<1.80   (13)

where

βWF2: a lateral magnification of the second focusing lens group uponfocusing on an infinity object in a wide angle end state.

The conditional expression (13) defines the lateral magnification of thesecond focusing lens group upon focusing on the infinity object in thewide angle end state. By satisfying the conditional expression (13), thevariation in various aberrations including the spherical aberration uponfocusing from the infinity object to the short-distant object in thewide angle end state can be suppressed.

If the corresponding value of the conditional expression (13) exceedsthe upper limit value of 1.80, the lateral magnification of the secondfocusing lens group upon focusing on the infinity object in the wideangle end state becomes too large. Accordingly, it is difficult tosuppress the variation in various aberrations including the sphericalaberration upon focusing from the infinity object to the short distantobject in the wide angle end state. To secure the advantageous effectsof this embodiment, it is preferable to set the upper limit value of theconditional expression (13) to 1.75. When the upper limit value of theconditional expression (13) is set to 1.70, 1.68, 1.65, 1.63, 1.60, 1.58or 1.55, or further to 1.54, the advantageous effects of this embodimentare further secured.

If the corresponding value of the conditional expression (13) fallsbelow the lower limit value of 1.05, the lateral magnification of thesecond focusing lens group upon focusing on the infinity object in thewide angle end state becomes too small. Accordingly, it is difficult tosuppress the variation in the distortion and the coma aberrationincluding the spherical aberration upon focusing from the infinityobject to the short distant object in the wide angle end state. Tosecure the advantageous effects of this embodiment, it is preferable toset the lower limit value of the conditional expression (13) to 1.08.When the lower limit value of the conditional expression (13) is set to1.10, 1.13, 1.15, 1.18, 1.20, 1.23, 1.24 or 1.28, or further to 1.30,the advantageous effects of this embodiment are further secured.

Preferably, the zoom optical system further satisfies the followingconditional expression (14).

(βWF1+1/βWF1)⁻²<0.250   (14)

where

βWF1: a lateral magnification of the first focusing lens group uponfocusing on an infinity object in a wide angle end state.

The conditional expression (14) defines the condition that the lateralmagnification of the first focusing lens group upon focusing on theinfinity object in the wide angle end state satisfies. By satisfying theconditional expression (14), the variation in various aberrationsincluding the spherical aberration, the distortion and the comaaberration upon focusing from the infinity object to the short-distantobject in the wide angle end state can be suppressed, while the amountof movement of the first focusing lens group can be reduced.

If the corresponding value of the conditional expression (14) exceedsthe upper limit value of 0.250, the amount of movement of the firstfocusing lens group upon focusing on the infinity object in the wideangle end state becomes too large, which is not preferable. To securethe advantageous effects of this embodiment, it is preferable to set theupper limit value of the conditional expression (14) to 0.249. When theupper limit value of the conditional expression (14) is set to 0.248,0.247 or 0.246, or further to 0.245, the advantageous effects of thisembodiment are further secured.

Preferably, the zoom optical system further satisfies the followingconditional expression (15).

(βWF2+1/βWF2)⁻²<0.250   (15)

where

βWF2: a lateral magnification of the second focusing lens group uponfocusing on an infinity object in a wide angle end state.

The conditional expression (15) defines the lateral magnification of thesecond focusing lens group upon focusing on the infinity object in thewide angle end state. By satisfying the conditional expression (15), thevariation in various aberrations including the spherical aberration, thedistortion and the coma aberration upon focusing from the infinityobject to the short-distant object in the wide angle end state can besuppressed, while the amount of movement of the second focusing lensgroup can be reduced.

If the corresponding value of the conditional expression (15) exceedsthe upper limit value of 0.249, the amount of movement of the secondfocusing lens group upon focusing on the infinity object in the wideangle end state becomes too large, which is not preferable. To securethe advantageous effects of this embodiment, it is preferable to set theupper limit value of the conditional expression (15) to 0.248. When theupper limit value of the conditional expression (15) is set to 0.245,0.240, 0.238, 0.235, 0.233, 0.230 or 0.228, or further to 0.225, theadvantageous effects of this embodiment are further secured.

The aforementioned optical apparatus is mounted with the zoom opticalsystem described above, which can achieve high-speed and silent autofocusing without increasing the size of the lens barrel, and favorablysuppress the aberration fluctuation upon zooming from the wide angle endstate to the telephoto end state, and the aberration fluctuation uponfocusing from the infinity object to the short distant object.

Subsequently, referring to FIG. 17, a method for manufacturing the zoomoptical system described above is schematically described. The zoomoptical system consists of a plurality of lens groups (ST1), and ismanufactured by disposing the configured lens groups in a lens barrel,under the following condition (ST2). The plurality of lens groups aredisposed such that distances between adjacent lens groups among theplurality of lens groups change upon zooming. The plurality of lensgroups herein disposed includes: a first focusing lens group that movesupon focusing; and a second focusing lens group that is disposed closerto an image surface than the first focusing lens group, and moves on atrajectory different from a trajectory of the first focusing lens groupupon focusing. The first focusing lens group and the second focusinglens group each have a negative refractive power. The plurality of lensgroups including two focusing lens groups are configured so as tosatisfy the aforementioned conditional expression (1).

The zoom optical system manufactured by the procedures described aboveand the optical apparatus mounted with the zoom optical system canachieve high-speed and silent auto focusing without increasing the sizeof the lens barrel, and favorably suppress the aberration fluctuationupon zooming from the wide angle end state to the telephoto end state,and the aberration fluctuation upon focusing from the infinity object tothe short distant object.

EXAMPLES

The aforementioned zoom optical system is further described exemplifyingfive numerical examples from a first example to a fifth example. First,the way of reading the diagrams and tables to be referred to bydescriptions of the examples is described.

FIGS. 1, 4, 7, 10 and 13 show the lens configurations and operations ofzoom optical systems in the respective examples. At the center of eachdiagram, the arrangement of lens groups are shown in a sectional view.At the lower part of each diagram, the movement trajectories of lensgroups G and an aperture stop S along the optical axis upon zooming froma wide angle end state (W) to a telephoto end state (T) are indicated byarrows on a two-dimensional plane. The horizontal axis of thetwo-dimensional plane indicates the position on the optical axis, andthe vertical axis indicates the state of the zoom optical system. At theupper part of each diagram, the movement trajectories (movementdirections and amounts of movement) of the focusing lens group uponfocusing from the infinity to the short distant object are indicated byarrows with characters of “FOCUSING” and “∞”.

In FIGS. 1, 4, 7, 10 and 13, each lens group is represented by acombination of a symbol G and a numeral, and each lens is represented bya combination of a symbol L and a numeral. In this Specification, toprevent complication due to increase in the number of symbols, numberingis made on an example-by-example basis. Accordingly, among multipleexamples, the combinations of the same symbols and numerals aresometimes used. However, this does not mean that the configurationsindicated by these combinations of the symbols and numerals are thesame.

FIGS. 2A-2C, 5A-5C, 8A-8C, 11A-11C and 14A-14C are various aberrationgraphs of the zoom optical systems in the respective examples uponfocusing on infinity. FIGS. 3A-3C, 6A-6C, 9A-9C, 12A-12C and 15A-15C arevarious aberration graphs of the zoom optical systems in the respectiveexamples upon focusing on a short distant object. In these graphs, FNOindicates the F-number, NA indicates the numerical aperture, and Yindicates the image height. The spherical aberration graph indicates thevalue of the F-number or the numerical aperture corresponding to themaximum diameter. The astigmatism graph and the distortion graph eachindicate the maximum value of the image height. The coma aberrationgraph indicates the value of each image height. The symbol d indicatesd-line (λ=587.6 nm). The symbol g indicates g-line (λ=435.8 nm). In theastigmatism graph, a solid line indicates a sagittal image surface, anda broken line indicates a meridional image surface. The graph of thechromatic aberration of magnification shows the chromatic aberration ofmagnification with reference to g-line.

Subsequently, tables used for the respective examples are described. Inthe table of [General Data], f indicates the focal length of the entirelens system, FNO indicates the F-number, 2ω indicates the angle of view(the unit is ° (degrees), and ω is the half angle of view), and Ymaxindicates the maximum image height. TL indicates a distance obtained byadding BF to the distance from the lens foremost surface to the lenslast surface on the optical axis upon focusing on infinity. BF indicatesthe air equivalent distance (back focus) from the lens last surface tothe image surface I on the optical axis upon focusing on infinity. Notethat these values are indicated for each of zoom states at thewide-angle end (W), the intermediate focal length (M) and the telephotoend (T).

In the table of [General Data], MWF1 indicates the absolute value of theamount of movement of the first focusing lens group upon focusing froman infinity object to a short-distant object (shortest-distant object)in the wide angle end state. MWF2 indicates the absolute value of theamount of movement of the second focusing lens group upon focusing fromthe infinity object to the short-distant object (shortest-distantobject) in the wide angle end state. βWF1 indicates the lateralmagnification of the first focusing lens group in the case of focusingon the infinity object in the wide angle end state. βWF2 indicates thelateral magnification of the second focusing lens group in the case offocusing on the infinity object in the wide angle end state.

In the table of [Lens Data], Surface Number indicates the order of theoptical surface from the object side along the direction in which theray travels, R indicates the radius of curvature (the surface whosecenter of curvature resides on the image side is regarded to have apositive value) of each optical surface, D indicates the surfacedistance, which is the distance to the next optical surface (or theimage surface) from each optical surface on the optical axis, nd is therefractive index of the material of the optical member for d-line, andvd indicates the Abbe number of the material of the optical member withrespect to d-line. (Aperture Stop S) indicates an aperture stop. Theradius of curvature “∞” indicates a plane or an aperture. Thedescription of the air refractive index nd=1.00000 is omitted. In a casewhere the lens surface is an aspherical surface, the surface number isassigned * symbol, and the field of the radius of curvature R indicatesthe paraxial radius of curvature.

In the table of [Aspherical Surface Data], the shape of the asphericalsurface indicated in [Lens Data] is indicated by the followingexpression (A). X(y) indicates the distance (sag amount) from thetangent plane at the vertex of the aspherical surface to the position onthe aspherical surface at the height y along the optical axis direction.R indicates the radius of curvature (paraxial radius of curvature) ofthe reference spherical surface. K indicates the conic constant. Aiindicates the i-th aspherical coefficient. “E-n” indicates “x10^(−n)”.For example, 1.234E−05=1.234×10⁻⁵. Note that the second-order asphericalcoefficient A2 is zero, and its description is omitted.

X(y)=(y ² /R)/{1+(1−κxy ² /R ²)^(1/2) }+A4xy ⁴ +A6xy ⁶ +A8xy ⁸ +A10xy ¹⁰A12xy ¹²   (A)

The table of [Lens Group Data] shows the first surface (the surfaceclosest to the object) and the focal length of each lens group.

The table of [Variable Distance Data] shows the surface distances atsurface numbers where the surface distance is “Variable” in the tableshowing [Lens Data]. Here, surface distances in the zoom states at thewide-angle end (W), the intermediate focal length (M) and the telephotoend (T) upon the infinity focus and the short range focus are indicated.

The table of [Conditional Expression Corresponding Value] shows thevalue corresponding to each conditional expression.

In general, “mm” is used as units for the focal length f, radius ofcurvature R, surface distance D, and other lengths. Accordingly, also ineach table in this Specification, the unit for length is “mm”. Note thatthe optical system can achieve equivalent optical performances even whenproportionally enlarged or proportionally reduced. Accordingly, the unitfor lengths is not necessarily limited to “mm”.

The descriptions of the diagrams and tables so far are common to all theexamples. Redundant descriptions are hereinafter omitted.

First Example

A first example is described with reference to FIGS. 1, 2A-2C and 3A-3Cand Table 1. FIG. 1 is a lens configuration diagram of a zoom opticalsystem according to the first example. The zoom optical system ZL(1)according to the first example consists of, in order from the object: afirst lens group G1 having a positive refractive power; a second lensgroup G2 having a negative refractive power; an aperture stop S; a thirdlens group G3 having a positive refractive power; a fourth lens group G4having a positive refractive power; a fifth lens group G5 (firstfocusing lens group) having a negative refractive power; a sixth lensgroup G6 (second focusing lens group) having a negative refractivepower; and a seventh lens group G7 having a positive refractive power.Here, the first to fourth lens groups G1 to G4 correspond to a precedinglens group GF, and the seventh lens group G7 corresponds to a succeedinglens group GR. The image surface I is disposed subsequent to the seventhlens group G7.

Upon zooming from the wide angle end state (W) to the telephoto endstate (T), the first to seventh lens groups G1 to G7 move along thetrajectories indicated by the arrows in the lower part of FIG. 1, whichchanges the distances between adjacent lens groups, and achieveszooming. Upon focusing, the fifth lens group G5 and the sixth lens groupG6 independently move in the directions (image surface direction)indicated by arrows in the upper part of FIG. 1 (along differenttrajectories), thus achieving focusing from the infinity object to theshort distant object.

The first lens group G1 consists of, in order from the object: anegative cemented lens that includes a negative meniscus lens L11 havinga convex surface facing the object, and a positive meniscus lens L12having a convex surface facing the object; and a positive meniscus lensL13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; abiconcave negative lens L22; a positive meniscus lens L23 having aconvex surface facing the object; and a negative meniscus lens L24having a concave surface facing the object. The negative meniscus lensL21 has an object-side surface that is an aspherical surface.

The third lens group G3 consists of, in order from the object: abiconvex positive lens L31; and a negative cemented lens that includes abiconvex positive lens L32, and a biconcave negative lens L33.

The fourth lens group G4 consists of, in order from the object: abiconvex positive lens L41; a negative cemented lens that includes abiconcave negative lens L42, and a biconvex positive lens L43; and abiconvex positive lens L44. The positive lens L41 has an object-sidesurface that is an aspherical surface. The positive lens L44 has animage-side surface that is an aspherical surface.

The fifth lens group G5 consists of, in order from the object: abiconvex positive lens L51; and a biconcave negative lens L52.

The sixth lens group G6 consists of a biconcave negative lens L61. Thenegative lens L61 has an object-side surface that is an asphericalsurface.

The seventh lens group G7 consists of a biconvex positive lens L71.

The following Table 1 lists values of data on the zoom optical systemaccording to the first example.

TABLE 1 [General Data] Zooming ratio = 2.74 MWF1 = 0.255 MWF2 = 0.618βWF1 = 1.418 βWF2 = 1.530 W M T f 24.8 50.0 67.9 FNO 2.92 2.92 2.92 2ω85.14 45.20 34.12 Ymax 21.60 21.60 21.60 TL 135.45 153.76 169.45 BF13.08 25.53 33.89 [Lens Data] Surface Number R D nd νd Object ∞ Surface 1 11820.3050 2.500 1.84666 23.80  2 254.8436 3.832 1.59319 67.90  31938.9860 0.200  4 81.3609 6.634 1.81600 46.59  5 717.8392 D5(Variable) 6* 170.2224 2.000 1.67798 54.89  7 19.0228 8.030  8 −102.7918 1.2001.59319 67.90  9 39.9274 0.200 10 30.7705 3.844 1.85000 27.03 11120.7450 4.556 12 −26.6990 1.200 1.60300 65.44 13 −48.1940 D13(Variable)14(Aperture ∞ 1.500 Stop S) 15 51.8883 3.971 1.90265 35.73 16 −335.10120.200 17 34.2757 7.394 1.49782 82.57 18 −32.4829 1.300 1.81600 46.59 19124.5969 D19(Variable)  20* 73.3752 4.605 1.82098 42.50 21 −40.94970.222 22 −60.6253 1.200 1.85478 24.80 23 23.2350 6.747 1.49782 82.57 24−68.9735 0.930 25 51.1526 5.532 1.80604 40.74  26* −59.8674D26(Variable) 27 364.3227 3.545 1.94595 17.98 28 −58.9057 0.200 29−87.4737 1.200 1.77250 49.62 30 26.6831 D30(Variable)  31* −54.37691.300 1.95150 29.83 32 226.2913 D32(Variable) 33 84.9939 5.357 1.8348142.73 34 −133.1562 BF Image ∞ Surface [Aspherical Surface Data] 6thSurface K = 1.0000 A4 = 2.79734E−06, A6 = −1.48626E−09, A8 =2.33651E−12, A10 = −3.91747E−17 20th Surface K = 1.0000 A4 =−1.24053E−05, A6 = 2.41375E−10, A8 = 1.23614E−11, A10 = −2.66251E−1426th Surface K = 1.0000 A4 = 1.94712E−06, A6 = −7.52657E−09, A8 =−2.53945E−12, A10 = 9.10643E−15 31st Surface K = 1.0000 A4 =−5.72467E−06, A6 = −2.85790E−08, A8 = 9.21679E−11, A10 = −4.86764E−13[Lens Group Data] First Focal Group surface length 1 1 129.519 2 6−21.862 3 14 47.382 4 20 28.141 5 27 −53.501 6 31 −45.973 7 33 62.847[Variable Distance Data] W M T W M T Short- Short- Short- InfinityInfinity Infinity distance distance distance D5 2.000 20.511 30.6872.000 20.511 30.687 D13 18.977 5.779 2.000 18.977 5.779 2.000 D19 9.0783.248 2.000 9.078 3.248 2.000 D26 2.614 2.197 2.001 2.869 2.555 2.431D30 7.108 7.282 6.363 7.472 7.442 6.438 D32 3.198 9.812 13.117 2.5799.294 12.612 [Conditional Expression Corresponding Value] ConditionalExpression (1) fF1/−fF2 = 1.164 Conditional Expression (2) (−fFs)/ft =0.677 Conditional Expression (3) (−fFs)/fw = 1.857 ConditionalExpression (4) MWF1/MWF2 = 0.412 Conditional Expression (5) βWF1/βWF2 =0.927 Conditional Expression (6) (−fFs)/fR = 0.732 ConditionalExpression (7) (−fFs)/fF = 1.634 Conditional Expression (8) f1/(−f2) =5.924 Conditional Expression (9) 2ωw = 85.14 Conditional Expression (10)BFw/fw = 0.529 Conditional Expression (11) (r2 + r1)/(r2 − r1) = 0.613Conditional Expression (12) βWF1 = 1.418 Conditional Expression (13)βWF2 = 1.530 Conditional Expression (14) (βWF1 + 1/βWF1)⁻² = 0.2218Conditional Expression (15) (βWF2 + 1/βWF2)⁻² = 0.2097

FIGS. 2A-2C shows various aberrations of the zoom optical systemaccording to the first example upon focusing on infinity in thewide-angle end state (2A), the intermediate focal length state (2B) andthe telephoto end state (2C). FIGS. 3A-3C shows various aberrations ofthe zoom optical system according to the first example upon focusing ona short distant object in the wide-angle end state (3A), theintermediate focal length state (3B) and the telephoto end state (3C).

The various aberration graphs show that the zoom optical systemaccording to the first example favorably corrects the variousaberrations from the wide-angle end state to the telephoto end state,has an excellent imaging performance, and also has an excellent imagingperformance even upon focusing on a short distant object.

Second Example

A second example is described with reference to FIGS. 4, 5A-5C and 6A-6Cand Table 2. FIG. 4 is a lens configuration diagram of a zoom opticalsystem according to the second example. The zoom optical system ZL(2)according to the second example consists of, in order from the object: afirst lens group G1 having a positive refractive power; a second lensgroup G2 having a negative refractive power; an aperture stop S; a thirdlens group G3 having a positive refractive power; a fourth lens group G4having a positive refractive power; a fifth lens group G5 (firstfocusing lens group) having a negative refractive power; a sixth lensgroup G6 (second focusing lens group) having a negative refractivepower; and a seventh lens group G7 having a positive refractive power.Here, the first to fourth lens groups G1 to G4 correspond to a precedinglens group GF, and the seventh lens group G7 corresponds to a succeedinglens group GR. The image surface I is disposed subsequent to the seventhlens group G7.

Upon zooming from the wide angle end state (W) to the telephoto endstate (T), the first to seventh lens groups G1 to G7 move along thetrajectories indicated by the arrows in the lower part of FIG. 4, whichchanges the distances between adjacent lens groups, and achieveszooming. Upon focusing, the fifth lens group G5 and the sixth lens groupG6 independently move in the directions (image surface direction)indicated by arrows in the upper part of FIG. 4 (along differenttrajectories), thus achieving focusing from a long-distance object to ashort distant object.

The first lens group G1 consists of, in order from the object: anegative cemented lens that includes a negative meniscus lens L11 havinga convex surface facing the object, and a positive meniscus lens L12having a convex surface facing the object; and a positive meniscus lensL13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; abiconcave negative lens L22; a positive meniscus lens L23 having aconvex surface facing the object; and a negative meniscus lens L24having a concave surface facing the object. The negative meniscus lensL21 has an object-side surface that is an aspherical surface.

The third lens group G3 consists of, in order from the object: apositive meniscus lens L31 having a convex surface facing the object;and a negative cemented lens that includes a biconvex positive lens L32,and a biconcave negative lens L33.

The fourth lens group G4 consists of, in order from the object: abiconvex positive lens L41; a negative cemented lens that includes abiconcave negative lens L42, and a biconvex positive lens L43; and abiconvex positive lens L44. The positive lens L41 has an object-sidesurface that is an aspherical surface.

The fifth lens group G5 consists of, in order from the object: abiconvex positive lens L51; and a biconcave negative lens L52.

The sixth lens group G6 consists of a negative meniscus lens L61 havinga concave surface facing the object. The negative meniscus lens L61 hasan object-side surface that is an aspherical surface.

The seventh lens group G7 consists of a biconvex positive lens L71. Thepositive lens L71 has an object-side surface that is an asphericalsurface.

TABLE 2 [General Data] Zooming ratio = 2.74 MWF1 = 0.274 MWF2 = 0.666βWF1 = 1.466 βWF2 = 1.399 W M T f 24.8 50.0 67.9 FNO 2.92 2.92 2.92 2ω85.14 45.14 33.98 Ymax 21.60 21.60 21.60 TL 136.45 152.83 166.55 BF11.75 22.94 28.76 [Lens Data] Surface Number R D nd νd Object ∞ Surface 1 11836.0180 2.500 1.84666 23.80  2 263.6060 3.519 1.81600 46.59  3996.8722 0.200  4 97.5302 5.847 1.81600 46.59  5 894.1609 D5(Variable) 6* 469.8262 2.000 1.58887 61.13  7 20.0932 8.459  8 −202.0263 1.2001.77250 49.62  9 46.2591 0.200 10 32.7348 4.789 1.75520 27.57 11757.6545 3.868 12 −30.1213 1.200 1.60300 65.44 13 −58.1128 D13(Variable)14(Aperture ∞ 1.500 Stop S) 15 43.9945 3.971 1.90265 35.73 16 1479.76600.603 17 33.0299 7.156 1.49782 82.57 18 −34.0457 1.300 1.81600 46.59 1992.8728 D19(Variable)  20* 124.2240 4.029 1.77387 47.25 21 −37.22280.200 22 −64.0093 1.200 1.85478 24.80 23 21.9014 6.529 1.59319 67.90 24−90.1349 0.921 25 48.3180 5.294 1.83400 37.18 26 −66.0132 D26(Variable)27 −1051.5067 3.250 1.94595 17.98 28 −55.5153 0.431 29 −85.9904 1.2001.69680 55.52 30 23.6335 D30(Variable)  31* −49.1357 1.300 1.95150 29.8332 −2454.5649 D32(Variable)  33* 121.4403 4.780 1.88202 37.22 34−126.7893 BF Image ∞ Surface [Aspherical Surface Data] 6th Surface K =1.0000 A4 = 3.12101E−06, A6 = −1.77766E−09, A8 = 2.07046E−12, A10 =−3.82388E−16 20th Surface K = 1.0000 A4 = −1.59181E−05, A6 =−3.41748E−10, A8 = 5.24280E−11, A10 = −1.12143E−13 31st Surface K =1.0000 A4 = −8.64573E−06, A6 = −1.85220E−08, A8 = 3.17657E−11, A10 =−2.40014E−13 33rd Surface K = 1.0000 A4 = 1.15695E−06, A6 = 7.52900E−10,A8 = −4.19329E−12, A10 = 4.10233E−15 [Lens Group Data] First Focal Groupsurface length 1 1 151.194 2 6 −25.501 3 14 49.576 4 20 27.755 5 27−47.512 6 31 −52.709 7 33 70.966 [Variable Distance Data] W M T W M TShort- Short- Short- Infinity Infinity Infinity distance distancedistance D5 2.000 21.966 33.591 2.000 21.966 33.591 D13 23.054 7.1222.000 23.054 7.122 2.000 D19 8.670 3.016 2.000 8.670 3.016 2.000 D262.760 2.196 2.542 3.034 2.530 2.948 D30 7.661 8.136 7.640 8.053 8.3787.816 D32 3.109 10.012 12.574 2.444 9.436 11.991 [Conditional ExpressionCorresponding Value] Conditional Expression (1) fF1/−fF2N = 0.901Conditional Expression (2) (−fFs)/ft = 0.700 Conditional Expression (3)(−fFs)/fw = 1.920 Conditional Expression (4) MWF1/MWF2 = 0.412Conditional Expression (5) βWF1/βWF2 = 1.048 Conditional Expression (6)(−fFs)/fR = 0.670 Conditional Expression (7) (−fFs)/fF = 1.712Conditional Expression (8) f1/(−f2) = 5.929 Conditional Expression (9)2ωw = 85.14 Conditional Expression (10) BFw/fw = 0.475 ConditionalExpression (11) (r2 + r1)/(r2 − r1) = 1.041 Conditional Expression (12)βWF1 = 1.466 Conditional Expression (13) βWF2 = 1.399 ConditionalExpression (14) (βWF1 + 1/βWF1)⁻² = 0.2167 Conditional Expression (15)(βWF2 + 1/βWF2)⁻² = 0.2238

FIGS. 5A-5C shows various aberrations of the zoom optical systemaccording to the second example upon focusing on infinity in thewide-angle end state (5A), the intermediate focal length state (5B) andthe telephoto end state (5C). FIGS. 6A-6C shows various aberrations ofthe zoom optical system according to the second example upon focusing ona short distant object in the wide-angle end state (6A), theintermediate focal length state (6B) and the telephoto end state (6C).

The various aberration graphs show that the zoom optical systemaccording to the second example favorably corrects the variousaberrations from the wide-angle end state to the telephoto end state,has an excellent imaging performance, and also has an excellent imagingperformance even upon focusing on a short distant object.

Third Example

A third example is described with reference to FIGS. 7, 8A-8C and 9A-9Cand Table 3. FIG. 7 is a lens configuration diagram of a zoom opticalsystem according to the third example. The zoom optical system ZL(3)according to the third example consists of, in order from the object: afirst lens group G1 having a positive refractive power; a second lensgroup G2 having a negative refractive power; an aperture stop S; a thirdlens group G3 having a positive refractive power; a fourth lens group G4(first focusing lens group) having a negative refractive power; a fifthlens group G5 (second focusing lens group) having a negative refractivepower; and a sixth lens group G6 having a positive refractive power.Here, the first to third lens groups G1 to G3 correspond to a precedinglens group GF, and the sixth lens group G6 corresponds to a succeedinglens group GR. The image surface I is disposed subsequent to the sixthlens group G6.

Upon zooming from the wide angle end state (W) to the telephoto endstate (T), the first to sixth lens groups G1 to G6 move along thetrajectories indicated by the arrows in the lower part of FIG. 7, whichchanges the distances between adjacent lens groups, and achieveszooming. Upon focusing, the fourth lens group G4 and the fifth lensgroup G5 independently move in the directions (image surface direction)indicated by arrows in the upper part of FIG. 7 (along differenttrajectories), thus achieving focusing from a long-distance object to ashort distant object.

The first lens group G1 consists of, in order from the object: anegative cemented lens that includes a negative meniscus lens L11 havinga convex surface facing the object, and a positive meniscus lens L12having a convex surface facing the object; and a positive meniscus lensL13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; anegative meniscus lens L22 having a concave surface facing the object; abiconvex positive lens L23; and a negative meniscus lens L24 having aconcave surface facing the object. The negative meniscus lens L21 has anobject-side surface that is an aspherical surface.

The third lens group G3 consists of, in order from the object: abiconvex positive lens L31; a negative cemented lens that includes abiconvex positive lens L32, and a biconcave negative lens L33; abiconvex positive lens L34; a negative cemented lens that includes abiconcave negative lens L35 and a biconvex positive lens L36; and abiconvex positive lens L37. The positive lens L34 has an object-sidesurface that is an aspherical surface. The positive lens L37 has animage-side surface that is an aspherical surface.

The fourth lens group G4 consists of, in order from the object: apositive meniscus lens L41 having a concave surface facing the object;and a negative meniscus lens L42 having a convex surface facing theobject.

The fifth lens group G5 consists of a negative meniscus lens L51 havinga concave surface facing the object. The negative meniscus lens L51 hasan object-side surface that is an aspherical surface.

The sixth lens group G6 consists of a biconvex positive lens L61.

The following Table 3 lists values of data on the zoom optical systemaccording to the third example.

TABLE 3 [General Data] Zooming ratio = 2.74 MWF1 = 0.419 MWF2 = 0.625βWF1 = 1.168 βWF2 = 1.427 W M T f 24.8 50.0 67.9 FNO 3.50 3.50 3.50 2ω85.10 45.60 34.40 Ymax 21.60 21.60 21.60 TL 135.45 152.59 169.45 BF11.75 18.25 23.91 [Lens Data] Surface Number R D nd νd Object ∞ Surface 1 800.0000 2.500 1.84666 23.80  2 149.2823 3.000 1.59319 67.90  3205.0385 0.200  4 75.1891 6.257 1.81600 46.59  5 947.1276 D5(Variable) 6* 500.0000 2.000 1.67798 54.89  7 18.8391 14.459   8 −25.1985 1.2001.59319 67.90  9 −118.4665 0.200 10 97.8539 3.812 1.85000 27.03 11−61.2035 1.947 12 −28.1128 1.200 1.60300 65.44 13 −45.1446 D13(Variable)14(Aperture ∞ 1.500 Stop S) 15 39.0407 5.431 1.75520 27.57 16 −150.53100.200 17 27.2134 6.774 1.49782 82.57 18 −75.8975 1.300 2.00069 25.46 1965.0385 2.024  20* 112.8457 3.574 1.66755 41.87 21 −42.5203 0.290 22−65.7387 1.200 1.85478 24.80 23 18.5000 7.483 1.49782 82.57 24 −72.54003.463 25 94.8511 5.524 1.72825 28.38  26* −33.9997 D26(Variable) 27−157.1254 2.312 1.94594 17.98 28 −66.1574 0.200 29 77.0731 1.200 1.8040046.60 30 30.1840 D30(Variable)  31* −20.0000 1.300 1.95150 29.83 32−39.9506 D32(Variable) 33 389.0189 2.631 1.84666 23.80 34 −287.6232 BFImage ∞ Surface [Aspherical Surface Data] 6th Surface K = 1.0000 A4 =9.81697E−06, A6 = −1.08680E−08, A8 = 1.23597E−11, A10 = −2.17136E−1520th Surface K = 1.0000 A4 = −2.26533E−05, A6 = 5.36979E−09, A8 =1.47314E−11, A10 = −1.43415E−14 26th Surface K = 1.0000 A4 =2.62785E−07, A6 = −1.29286E−08, A8 = −4.74230E−12, A10 = −5.79020E−1431st Surface K = 1.0000 A4 = 1.10646E−06, A6 = −1.33919E−08, A8 =2.15561E−11, A10 = −5.38428E−13 [Lens Group Data] First Focal Groupsurface length 1 1 154.131 2 6 −25.881 3 14 30.388 4 27 −131.942 5 31−43.472 6 33 195.660 [Variable Distance Data] W M T W M T Short- Short-Short- Infinity Infinity Infinity distance distance distance D5 2.00018.585 26.409 2.000 18.585 26.409 D13 22.225 5.535 2.000 22.225 5.5352.000 D26 2.386 3.229 2.000 2.805 3.825 2.582 D30 10.756 9.234 9.37710.962 9.079 9.166 D32 3.151 14.573 22.575 2.526 14.132 22.204[Conditional Expression Corresponding Value] Conditional Expression (1)fF1/−fF2 = 3.035 Conditional Expression (2) (−fFs)/ft = 0.640Conditional Expression (3) (−fFs)/fw = 1.756 Conditional Expression (4)MWF1/MWF2 = 0.671 Conditional Expression (5) βWF1/βWF2 = 0.819Conditional Expression (6) (−fFs)/fR = 0.222 Conditional Expression (7)(−fFs)/fF = 1.431 Conditional Expression (8) f1/(−f2) = 5.955Conditional Expression (9) 2ωw = 85.10 Conditional Expression (10)BFw/fw = 0.475 Conditional Expression (11) (r2 + r1)/(r2 − r1) = 3.005Conditional Expression (12) βWF1 = 1.168 Conditional Expression (13)βWF2 = 1.427 Conditional Expression (14) (βWF1 + 1/βWF1)⁻² = 0.2440Conditional Expression (15) (βWF2 + 1/βWF2)⁻² = 0.2096

FIGS. 8A-8C shows various aberrations of the zoom optical systemaccording to the third example upon focusing on infinity in thewide-angle end state (8A), the intermediate focal length state (8B) andthe telephoto end state (8C). FIGS. 9A-9C shows various aberrations ofthe zoom optical system according to the third example upon focusing ona short distant object in the wide-angle end state (9A), theintermediate focal length state (9B) and the telephoto end state (9C).

The various aberration graphs show that the zoom optical systemaccording to the third example favorably corrects the variousaberrations from the wide-angle end state to the telephoto end state,has an excellent imaging performance, and also has an excellent imagingperformance even upon focusing on a short distant object.

Fourth Example

A fourth example is described with reference to FIGS. 10, 11A-11C and12A-12C and Table 4. FIG. 10 is a lens configuration diagram of a zoomoptical system according to the fourth example. The zoom optical systemZL(4) according to the fourth example consists of, in order from theobject: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; a third lensgroup G3 having a negative refractive power; an aperture stop S; afourth lens group G4 having a positive refractive power; a fifth lensgroup G5 (first focusing lens group) having a negative refractive power;a sixth lens group G6 (second focusing lens group) having a negativerefractive power; and a seventh lens group G7 having a positiverefractive power. Here, the first to fourth lens groups G1 to G4correspond to a preceding lens group GF, and the seventh lens group G7corresponds to a succeeding lens group GR. The image surface I isdisposed subsequent to the seventh lens group G7.

Upon zooming from the wide angle end state (W) to the telephoto endstate (T), the first to seventh lens groups G1 to G7 move along thetrajectories indicated by the arrows in the lower part of FIG. 10, whichchanges the distances between adjacent lens groups, and achieveszooming. Upon focusing, the fifth lens group G5 and the sixth lens groupG6 independently move in the directions (image surface direction)indicated by arrows in the upper part of FIG. 10 (along differenttrajectories), thus achieving focusing from a long-distance object to ashort distant object.

The first lens group G1 consists of, in order from the object: anegative cemented lens that includes a negative meniscus lens L11 havinga convex surface facing the object, and a positive meniscus lens L12having a convex surface facing the object; and a positive meniscus lensL13 having a convex surface facing the object.

The second lens group G2 consists of a negative meniscus lens L21 havinga convex surface facing the object. The negative meniscus lens L21 hasan object-side surface that is an aspherical surface.

The third lens group G3 consists of, in order from the object: anegative meniscus lens L31 having a concave surface facing the object; abiconvex positive lens L32; and a negative meniscus lens L33 having aconcave surface facing the object.

The fourth lens group G4 consists of, in order from the object: abiconvex positive lens L41; a negative cemented lens that includes abiconvex positive lens L42, and a biconcave negative lens L43; abiconvex positive lens L44; a negative cemented lens that includes abiconcave negative lens L45 and a biconvex positive lens L46; and abiconvex positive lens L47. The positive lens L44 has an object-sidesurface that is an aspherical surface. The positive lens L47 has animage-side surface that is an aspherical surface.

The fifth lens group G5 consists of, in order from the object: apositive meniscus lens L51 having a concave surface facing the object;and a negative meniscus lens L52 having a convex surface facing theobject.

The sixth lens group G6 consists of a negative meniscus lens L61 havinga concave surface facing the object. The negative meniscus lens L61 hasan object-side surface that is an aspherical surface.

The seventh lens group G7 consists of a biconvex positive lens L71.

The following Table 4 lists values of data on the zoom optical systemaccording to the fourth example.

TABLE 4 [General Data] Zooming ratio = 2.74 MWF1 = 0.375 MWF2 = 0.564βWF1 = 1.173 βWF2 = 1.459 W M T f 24.8 50.0 67.9 FNO 3.50 3.50 3.50 2ω85.08 45.84 34.44 Ymax 21.60 21.60 21.60 TL 135.43 152.96 169.45 BF11.75 20.53 22.23 [Lens Data] Surface Number R D nd νd Object ∞ Surface 1 800.0000 2.500 1.84666 23.80  2 161.6173 3.000 1.59319 67.90  3233.4567 0.200  4 88.3647 5.578 1.81600 46.59  5 1494.7667 D5(Variable) 6* 500.0000 2.000 1.67798 54.89  7 20.0442 D7(Variable)  8 −23.69091.200 1.59319 67.90  9 −99.5585 0.200 10 130.0428 3.826 1.85000 27.03 11−52.3275 1.221 12 −32.7025 1.200 1.60300 65.44 13 −46.7034 D13(Variable)14(Aperture ∞ 1.658 Stop S) 15 42.4477 4.725 1.75520 27.57 16 −240.92191.366 17 27.1858 6.996 1.49782 82.57 18 −51.9273 1.300 2.00069 25.46 1950.0514 2.382  20* 108.1669 2.719 1.66755 41.87 21 −76.2004 0.200 22−3410.9598 1.200 1.85478 24.80 23 20.2029 7.635 1.49782 82.57 24−49.1628 1.439 25 149.7679 6.074 1.72825 28.38  26* −30.1914D26(Variable) 27 −162.6654 2.460 1.94594 17.98 28 −61.8074 0.200 2986.8437 2.035 1.80400 46.60 30 28.2564 D30(Variable)  31* −20.2693 1.3001.95150 29.83 32 −44.8147 D32(Variable) 33 15425.4800 2.506 1.8466623.80 34 −190.6511 BF Image ∞ Surface [Aspherical Surface Data] 6thSurface K = 1.0000 A4 = 7.50942E−06, A6 = −6.77248E−09, A8 =6.81523E−12, A10 = −1.86349E−15 20th Surface K = 1.0000 A4 =−2.45608E−05, A6 = −6.09341E−09, A8 = 4.23890E−11, A10 = −3.30984E−1326th Surface K = 1.0000 A4 = −1.46127E−06, A6 = −1.78339E−08, A8 =1.84178E−11, A10 = −1.65357E−13 31st Surface K = 1.0000 A4 =−1.14793E−07, A6 = −2.17369E−08, A8 = 6.66752E−11, A10 = −6.03155E−13[Lens Group Data] First Focal Group surface length 1 1 176.909 2 6−30.851 3 8 −1135.437 4 14 29.673 5 27 −109.998 6 31 −39.925 7 33222.447 [Variable Distance Data] W M T W M T Short- Short- Short-Infinity Infinity Infinity distance distance distance D5 2.000 19.89729.314 2.000 19.897 29.314 D7 17.679 14.397 13.852 17.679 14.397 13.852D13 20.371 5.813 2.000 20.371 5.813 2.000 D26 4.463 2.867 2.000 4.8383.299 2.417 D30 8.754 8.749 8.885 8.943 8.714 8.824 D32 3.289 13.58624.053 2.725 13.189 23.697 [Conditional Expression Corresponding Value]Conditional Expression (1) fF1/−fF2 = 2.755 Conditional Expression (2)(−fFs)/ft = 0.588 Conditional Expression (3) (−fFs)/fw = 1.613Conditional Expression (4) MWF1/MWF2 = 0.665 Conditional Expression (5)βWF1/βWF2 = 0.804 Conditional Expression (6) (−fFs)/fR = 0.179Conditional Expression (7) (−fFs)/fF = 1.346 Conditional Expression (8)f1/(−f2) = 5.734 Conditional Expression (9) 2ωw = 85.08 ConditionalExpression (10) BFw/fw = 0.475 Conditional Expression (11) (r2 + r1)/(r2− r1) = 2.652 Conditional Expression (12) βWF1 = 1.1727 ConditionalExpression (13) βWF2 = 1.4585 Conditional Expression (14) (βWF1 +1/βWF1)⁻² = 0.2438 Conditional Expression (15) (βWF2 + 1/βWF2)⁻² =0.2175

FIGS. 11A-11C shows various aberrations of the zoom optical systemaccording to the fourth example upon focusing on infinity in thewide-angle end state (11A), the intermediate focal length state (11B)and the telephoto end state (11C). FIGS. 12A-12C shows variousaberrations of the zoom optical system according to the fourth exampleupon focusing on a short distant object in the wide-angle end state(12A), the intermediate focal length state (12B) and the telephoto endstate (12C).

The various aberration graphs show that the zoom optical systemaccording to the fourth example favorably corrects the variousaberrations from the wide-angle end state to the telephoto end state,has an excellent imaging performance, and also has an excellent imagingperformance even upon focusing on a short distant object.

Fifth Example

A fifth example is described with reference to FIGS. 13, 14A-14C and15A-15C and Table 5. FIG. 13 is a lens configuration diagram of a zoomoptical system according to the fifth example. The zoom optical systemZL(5) according to the fifth example consists of, in order from theobject: a first lens group G1 having a positive refractive power; asecond lens group G2 having a negative refractive power; an aperturestop S; a third lens group G3 having a positive refractive power; afourth lens group G4 having a positive refractive power; a fifth lensgroup G5 (first focusing lens group) having a negative refractive power;a sixth lens group G6 (second focusing lens group) having a negativerefractive power; a seventh lens group G7 having a positive refractivepower; and an eighth lens group G8 having a positive refractive power.Here, the first to fourth lens groups G1 to G4 correspond to a precedinglens group GF, and the seventh lens group G7 and the eighth lens groupsG8 correspond to a succeeding lens group GR. The image surface I isdisposed subsequent to the eighth lens group G8.

Upon zooming from the wide angle end state (W) to the telephoto endstate (T), the first to eighth lens groups G1 to G8 move along thetrajectories indicated by the arrows in the lower part of FIG. 13, whichchanges the distances between adjacent lens groups, and achieveszooming. Upon focusing, the fifth lens group G5 and the sixth lens groupG6 independently move in the directions (image surface direction)indicated by arrows in the upper part of FIG. 13 (along differenttrajectories), thus achieving focusing from a long-distance object to ashort distant object.

The first lens group G1 consists of, in order from the object: anegative cemented lens that includes a negative meniscus lens L11 havinga convex surface facing the object, and a positive meniscus lens L12having a convex surface facing the object; and a positive meniscus lensL13 having a convex surface facing the object.

The second lens group G2 consists of, in order from the object: anegative meniscus lens L21 having a convex surface facing the object; abiconcave negative lens L22; a positive meniscus lens L23 having aconvex surface facing the object; and a negative meniscus lens L24having a concave surface facing the object. The negative meniscus lensL21 has an object-side surface that is an aspherical surface.

The third lens group G3 consists of, in order from the object: abiconvex positive lens L31; and a positive cemented lens that includes abiconvex positive lens L32, and a biconcave negative lens L33.

The fourth lens group G4 consists of, in order from the object: abiconvex positive lens L41; a negative cemented lens that includes abiconcave negative lens L42, and a biconvex positive lens L43; and abiconvex positive lens L44. The positive lens L41 has an object-sidesurface that is an aspherical surface. The positive lens L44 has animage-side surface that is an aspherical surface.

The fifth lens group G5 consists of, in order from the object: abiconvex positive lens L51; and a biconcave negative lens L52.

The sixth lens group G6 consists of a biconcave negative lens L61. Thenegative lens L61 has an object-side surface that is an asphericalsurface.

The seventh lens group G7 consists of a biconvex positive lens L71.

The eighth lens group G8 consists of a positive meniscus lens L81 havinga concave surface facing the object.

The following Table 5 lists values of data on the zoom optical systemaccording to the fifth example.

TABLE 5 [General Data] Zooming ratio = 2.74 MWF1 = 0.201 MWF2 = 0.694βWF1 = 1.405 βWF2 = 1.534 W M T f 24.8 50.0 67.9 FNO 2.92 2.92 2.92 2ω85.18 45.24 34.12 Ymax 21.60 21.60 21.60 TL 135.45 154.15 169.45 BF11.38 23.63 31.35 [Lens Data] Surface Number R D nd νd Object ∞ Surface 1 11891.6830 2.500 1.84666 23.80  2 259.8551 3.953 1.59319 67.90  34532.4082 0.200  4 82.2793 6.511 1.81600 46.59  5 637.5320 D5(Variable) 6* 166.9549 2.000 1.67798 54.89  7 18.9915 7.826  8 −128.0661 1.2001.59319 67.90  9 39.3297 0.200 10 30.2329 3.805 1.85000 27.03 11108.1671 4.249 12 −26.7310 1.200 1.60300 65.44 13 −50.1190 D13(Variable)14(Aperture ∞ 1.500 Stop S) 15 52.2117 3.906 1.90265 35.72 16 −426.98130.200 17 36.5119 7.383 1.49782 82.57 18 −31.0542 1.300 1.81600 46.59 19191.2416 D19(Variable)  20* 83.3066 4.681 1.82098 42.50 21 −38.99880.299 22 −52.7599 1.200 1.85478 24.80 23 26.2315 6.594 1.49782 82.57 24−62.9470 0.212 25 52.3086 5.490 1.80604 40.74  26* −58.3708D26(Variable) 27 592.1811 3.338 1.94594 17.98 28 −62.8662 0.200 29−106.8070 1.200 1.77250 49.62 30 28.0432 D30(Variable)  31* −84.04361.300 1.95150 29.83 32 101.0812 D32(Variable) 33 76.7980 4.332 1.8348142.73 34 −571.5236 D34(Variable) 35 −84.4248 2.428 1.67252 26.52 36−64.1857 BF Image ∞ Surface [Aspherical Surface Data] 6th Surface K =1.0000 A4 = 2.89860E−06, A6 = −1.09792E−09, A8 = 1.24848E−12, A10 =1.65714E−15 20th Surface K = 1.0000 A4 = −1.21758E−05, A6 = 2.33795E−10,A8 = 1.34229E−11, A10 = −2.74633E−14 26th Surface K = 1.0000 A4 =2.89243E−06, A6 = −6.52485E−09, A8 = 1.47471E−14, A10 = 1.05852E−14 31stSurface K = 1.0000 A4 = −5.73632E−06, A6 = −2.30482E−08, A8 =6.15426E−11, A10 = −2.77958E−13 [Lens Group Data] First Focal Groupsurface length 1 1 130.490 2 6 −21.991 3 14 47.900 4 20 27.873 5 27−56.211 6 31 −48.064 7 33 81.345 8 35 379.801 [Variable Distance Data] WM T W M T Short- Short- Short- Infinity Infinity Infinity distancedistance distance D5 2.000 20.708 31.055 2.000 20.708 31.055 D13 18.8355.825 2.000 18.835 5.825 2.000 D19 9.480 3.315 2.000 9.480 3.315 2.000D26 2.777 2.126 2.000 2.977 2.460 2.419 D30 6.407 6.601 5.787 6.9016.815 5.893 D32 3.039 10.144 13.339 2.345 9.596 12.814 D34 2.329 2.5942.721 2.329 2.594 2.721 [Conditional Expression Corresponding Value]Conditional Expression (1) fF1/−fF2 = 1.170 Conditional Expression (2)(−fFs)/ft = 0.708 Conditional Expression (3) (−fFs)/fw = 1.942Conditional Expression (4) MWF1/MWF2 = 0.289 Conditional Expression (5)βWF1/βWF2 = 0.916 Conditional Expression (6) (−fFs)/fR = 0.702Conditional Expression (7) (−fFs)/fF = 1.724 Conditional Expression (8)f1/(−f2) = 5.934 Conditional Expression (9) 2ωw = 85.18 ConditionalExpression (10) BFw/fw = 0.460 Conditional Expression (11) (r2 + r1)/(r2− r1) = 0.092 Conditional Expression (12) βWF1 = 1.405 ConditionalExpression (13) βWF2 = 1.534 Conditional Expression (14) (βWF1 +1/βWF1)⁻² = 0.2232 Conditional Expression (15) (βWF2 + 1/βWF2)⁻² =0.2093

FIGS. 14A-14C shows various aberrations of the zoom optical systemaccording to the fifth example upon focusing on infinity in thewide-angle end state (14A), the intermediate focal length state (14B)and the telephoto end state (14C). FIGS. 15A-15C shows variousaberrations of the zoom optical system according to the fifth exampleupon focusing on a short distant object in the wide-angle end state(15A), the intermediate focal length state (15B) and the telephoto endstate (15C).

The various aberration graphs show that the zoom optical systemaccording to the fifth example favorably corrects the variousaberrations from the wide-angle end state to the telephoto end state,has an excellent imaging performance, and also has an excellent imagingperformance even upon focusing on a short distant object.

According to each embodiment described above, the reduction in size andweight of the lens groups for focusing can achieve high-speed AF andquietness during AF without increasing the size of the lens barrel, andcan further achieve a zoom optical system that favorably suppress theaberration fluctuation upon zooming from the wide angle end state to thetelephoto end state, and the aberration fluctuation upon focusing fromthe infinity object to the short distant object.

Note that the invention of the present application is not limited to theembodiments described above, and can be appropriately changed in a rangewithout degrading the optical performances identified by thedescriptions of corresponding claims.

The aforementioned examples describe the zoom optical systems that havethe six-group configuration, the seven-group configuration, and theeight-group configuration. Alternatively, zoom optical systems havingother group configurations (e.g., a nine-group configuration or the likewhere a lens or a lens group are added at a position in the zoom opticalsystem closest to the object or the image) can be adopted. Here, thelens group indicates a portion that includes at least one lens separatedby air distances changing during zooming.

Any of a spherical surface, a plane, and an aspherical surface may beadopted as each of the lenses constituting the zoom optical system ofthe present application. Spherical and planar lens surfaces haveadvantages that can facilitate lens processing and assembling andadjustment, prevent the optical performance degradation due to an errorin the lens processing and assembling and adjustment, and reduce thedegradation in representation performance even with the image surfacebeing misaligned. The lens surface that is an aspherical surface may beany of an aspherical surface made by a grinding process, a glass moldaspherical surface made by forming glass into an aspherical shape with amold, and a composite type aspherical surface made by forming a resin ona surface of glass into an aspherical shape. The lens surface may be adiffractive surface. The lens may be a gradient-index lens (GRIN lens),or a plastic lens.

An antireflection film having a high transmissivity in a wide wavelengthregion may be applied onto the lens surfaces of the lenses constitutingthe zoom optical systems of the present application. Accordingly, flaresand ghosts can be reduced, and high optical performances having a highcontrast can be achieved.

EXPLANATION OF NUMERALS AND CHARACTERS

-   G1 First lens group-   G2 Second lens group-   G3 Third lens group-   G4 Fourth lens group-   G5 Fifth lens group-   G6 Sixth lens group-   G7 Seventh lens group-   G8 Eighth lens group-   I Image surface-   S Aperture stop

1. A zoom optical system comprising a plurality of lens groups, whereindistances between adjacent lens groups among the plurality of lensgroups change upon zooming, the plurality of lens groups include: afirst focusing lens group that moves upon focusing; and a secondfocusing lens group that is disposed closer to an image surface than thefirst focusing lens group, and moves on a trajectory different from atrajectory of the first focusing lens group upon focusing, the firstfocusing lens group and the second focusing lens group each have anegative refractive power, and the following conditional expression issatisfied:0.40<fF1/fF2<3.50 where fF1: a focal length of the first focusing lensgroup, and fF2: a focal length of the second focusing lens group.
 2. Thezoom optical system according to claim 1, wherein the followingconditional expression is satisfied:0.20<(−fFs)/ft<2.00 fFs: a focal length of either the first focusinglens group or the second focusing lens group which has a strongerrefractive power than the other, and ft: a focal length of the zoomoptical system in a telephoto end state.
 3. The zoom optical systemaccording to claim 1, wherein the first focusing lens group moves in adirection toward the image surface upon focusing from an infinity objectto a short distant object.
 4. The zoom optical system according to claim1, wherein the second focusing lens group moves in a direction towardthe image surface upon focusing from an infinity object to a shortdistant object.
 5. The zoom optical system according to claim 1, whereinthe following conditional expression is satisfied:1.00<(−fFs)/fw<4.00 where fFs: a focal length of either the firstfocusing lens group or the second focusing lens group which has astronger refractive power than the other, and fw: a focal length of thezoom optical system in a wide angle end state.
 6. The zoom opticalsystem according to claim 1, wherein the following conditionalexpression is satisfied:0. 10<MWF1/MWF2<3.00 where MWF1: an absolute value of an amount ofmovement of the first focusing lens group upon focusing from an infinityobject to a short distant object in a wide angle end state, and MWF2: anabsolute value of an amount of movement of the second focusing lensgroup upon focusing from the infinity object to the short distant objectin the wide angle end state.
 7. The zoom optical system according toclaim 1, wherein the following conditional expression is satisfied:20<βWF1/βWF2<5.00 where βWF1: a lateral magnification of the firstfocusing lens group upon focusing on an infinity object in a wide angleend state, and βWF2: a lateral magnification of the second focusing lensgroup upon focusing on the infinity object in the wide angle end state.8. The zoom optical system according to claim 1, wherein the pluralityof lens groups include a succeeding lens group disposed closer to theimage surface than the second focusing lens group, and the succeedinglens group consists of at least one lens group.
 9. The zoom opticalsystem according to claim 1, wherein the plurality of lens groupsinclude a succeeding lens group disposed closer to the image surfacethan the second focusing lens group, and the following conditionalexpression is satisfied:−2.00<(−fFs)/fR<2.00 where fFs: a focal length of either the firstfocusing lens group or the second focusing lens group which has astronger refractive power than the other, and fR: a focal length of thesucceeding lens group.
 10. The zoom optical system according to claim 1,wherein the plurality of lens groups include a preceding lens groupdisposed closer to an object than the first focusing lens group, and thepreceding lens group consists of at least one lens group.
 11. The zoomoptical system according to claim 1, wherein the plurality of lensgroups include a preceding lens group disposed closer to an object thanthe first focusing lens group, and the following conditional expressionis satisfied:0.30<(−fFs)/fF<3.00 where fFs: a focal length of either the firstfocusing lens group or the second focusing lens group which has astronger refractive power than the other, and fF: a focal length of alens group adjacent to the first focusing lens group among lens groupsconsisting of the preceding lens group.
 12. The zoom optical systemaccording to claim 1, wherein the plurality of lens groups include apreceding lens group disposed closer to an object than the firstfocusing lens group, and the preceding lens group includes a first lensgroup that has a positive refractive power and is disposed closest to anobject.
 13. The zoom optical system according to claim 1, wherein theplurality of lens groups include a preceding lens group disposed closerto an object than the first focusing lens group, and the preceding lensgroup includes: a first lens group that has a positive refractive powerand is disposed closest to the object; and a second lens group that hasa negative refractive power and is disposed adjacent to an image surfaceof the first lens group.
 14. The zoom optical system according to claim1, wherein the plurality of lens groups include, in order closest froman object: a first lens group having a positive refractive power; and asecond lens group having a negative refractive power, and the followingconditional expression is satisfied:4.00<f1/(−f2)<8.00 where f1: a focal length of the first lens group, andf2: a focal length of the second lens group.
 15. The zoom optical systemaccording to claim 1, wherein the following conditional expression issatisfied:2ωw>75.0° where ωw: a half angle of view of the zoom optical system in awide angle end state.
 16. The zoom optical system according to claim 1,wherein the following conditional expression is satisfied:0.10<BFw/fw<1.00 where BFw: a back focus of the zoom optical system in awide-angle end state, and fw: a focal length of the zoom optical systemin the wide angle end state.
 17. The zoom optical system according toclaim 1, wherein the second focusing lens group has a lens componenthaving a negative refractive power, and the lens component satisfies thefollowing conditional expression:−2.00<(r2+r1)/(r2−r1)<6.00 where r1: a radius of curvature of a lenssurface of the lens component on an object side, and r2: a radius ofcurvature of a lens surface of the lens component on an image side. 18.The zoom optical system according to claim 1, wherein the followingconditional expression is satisfied:1.05<βWF1<1.80 where βWF1: a lateral magnification of the first focusinglens group upon focusing on an infinity object in a wide angle endstate.
 19. The zoom optical system according to claim 1, wherein thefollowing conditional expression is satisfied:1.05<βWF2<1.80 where βWF2: a lateral magnification of the secondfocusing lens group upon focusing on an infinity object in a wide angleend state.
 20. The zoom optical system according to claim 1, wherein thefollowing conditional expression is satisfied:(βWF1+1/βWF1)⁻²<0.250 where βWF1: a lateral magnification of the firstfocusing lens group upon focusing on an infinity object in a wide angleend state.
 21. The zoom optical system according to claim 1, wherein thefollowing conditional expression is satisfied:(βWF2+1/βWF2)⁻²<0.250 where βWF2: a lateral magnification of the secondfocusing lens group upon focusing on an infinity object in a wide angleend state.
 22. An optical apparatus mounted with the zoom optical systemaccording to claim
 1. 23. A method for manufacturing a zoom opticalsystem comprising a plurality of lens groups, wherein distances betweenadjacent lens groups among the plurality of lens groups change uponzooming, the plurality of lens groups include: a first focusing lensgroup that moves upon focusing; and a second focusing lens group that isdisposed closer to an image surface than the first focusing lens group,and moves on a trajectory different from a trajectory of the firstfocusing lens group upon focusing, the first focusing lens group and thesecond focusing lens group each have a negative refractive power, andthe method configures each of the lens groups and arranges the groups ina lens barrel so as to satisfy the following conditional expression:40<fF1/fF2<3.50 where fF1: a focal length of the first focusing lensgroup, and fF2: a focal length of the second focusing lens group.